Viscoelastic plastic interlayer for vibro-acoustic damping and glazing comprising such an interlayer

Abstract

A viscoelastic plastic interlayer can be incorporated between two glass sheets to form a laminated glazing with vibro-acoustic damping properties. The interlayer includes at least one layer made of viscoelastic plastic with vibro-acoustic damping properties. The interlayer is tinted in the bulk at least on a part of its surface. The interlayer is such that the resonant frequency f 2 of the second resonance mode of a laminated glazing bar with a surface area of 25 mm×300 mm composed of two glass sheets each 2.1 mm thick, between which is incorporated the interlayer, determined by measuring the mechanical impedance (MIM) at 20° C. according to standard ISO 16940, is between 760 Hz and 1000 Hz and the loss factor η 2 of the second resonance mode of the bar, determined by MIM under the same conditions, is greater than or equal to 0.25.

The invention claimed is: 
     
       1. A viscoelastic plastic interlayer to be incorporated between two glass sheets to form a laminated glazing with vibro-acoustic damping properties, the interlayer comprising:
 at least one layer made of viscoelastic plastic with vibro-acoustic damping properties, 
 the interlayer being tinted in the bulk at least on a part of a surface of the interlayer, 
 the interlayer being such that a resonant frequency f 2  of a second resonance mode of a laminated glazing bar with a surface area of 25 mm×300 mm composed of two glass sheets each 2.1 mm thick, between which is incorporated the interlayer, determined by measuring a mechanical impedance (MIM) at 20° C. according to standard ISO 16940, is between 760 Hz and 1000 Hz and a loss factor η 2  of the second resonance mode of the laminated glazing bar, determined by MIM under the same conditions, is greater than or equal to 0.25. 
 
     
     
       2. The interlayer according to  claim 1 , in which the layer includes polyvinyl butyral and plasticizer. 
     
     
       3. The interlayer according to  claim 1 , in which the resonant frequency f 2  is between 800 and 900 Hz. 
     
     
       4. The interlayer according to  claim 1 , in which the loss factor η 2  is greater than 0.30. 
     
     
       5. The interlayer according to  claim 1 , further comprising:
 two outer layers made of standard polyvinyl butyral (PVB), the layer being between the two outer layers. 
 
     
     
       6. The interlayer according to  claim 1 , in which the measurement of the mechanical impedance is performed at least one month after assembly of the laminated glazing bar, the laminated glazing bar having been assembled at least one month after manufacture of the interlayer. 
     
     
       7. A glazing, comprising:
 a first glass sheet between 0.5 mm and 2.6 mm thick, 
 a second glass sheet between 0.5 mm and 1.6 mm thick, 
 the interlayer according to  claim 1 , the interlayer being between the first and second glass sheets, 
 in which a total thickness of the first and second glass sheets is less than 3.7 mm. 
 
     
     
       8. The glazing according to  claim 7 , in which the interlayer is tinted only in an upper part. 
     
     
       9. The glazing according to  claim 7 , in which the interlayer is tinted over an entire surface. 
     
     
       10. A motor vehicle, comprising:
 the glazing according to  claim 7 , the first glass sheet between 0.5 mm and 2.6 mm thick being turned facing an exterior of the vehicle and the second glass sheet between 0.5 mm and 1.6 mm thick being turned facing an interior of the vehicle. 
 
     
     
       11. The glazing according to  claim 7 , wherein the glazing is a motor vehicle windscreen. 
     
     
       12. The glazing according to  claim 7 , wherein the glazing is as a windscreen, a front side window, a rear side window, a rear window or a quarter glass of a motor vehicle. 
     
     
       13. The interlayer according to  claim 1 , in which the resonant frequency f 2  is between 800 and 850 Hz. 
     
     
       14. The glazing according to  claim 7 , wherein the first glass sheet is between 1.4 mm and 2.0 mm thick and the second glass sheet is between 1.1 mm and 1.5 mm thick. 
     
     
       15. The glazing according to  claim 7 , wherein the first glass sheet is 1.8 mm thick and the second glass sheet is 1.4 mm thick. 
     
     
       16. The glazing according to  claim 7 , wherein the first glass sheet is 1.6 mm thick and the second glass sheet is 1.2 mm thick. 
     
     
       17. The glazing according to  claim 7 , wherein the first glass sheet is 1.4 mm thick and the second glass sheet is 1.1 mm thick.